Runoff velocity controls soil nitrogen leaching in subtropical restored forest in southern China

•NH4+-N, TN mainly leached through sediment, whereas NO3‾-N through runoff.•Runoff velocity was a critical driver of N leaching.•Preferenceshould begivento Pinus elliottii to minimize N leaching. Nitrogen (N) leaching is a complex process regulating N exchange between the soil and aquatic ecosystems and may result in groundwater pollution, threatening ecosystem security. However, the mechanisms driving N leaching in subtropical forests have not been fully elucidated. Here, we present a quantitative analysis of vegetation-soil relationships in response to N leaching in a subtropical forest located in southern China. The results reveal that N leaching in runoff at lower simulated precipitation intensities (60 mm/h, 90 mm/h) and in sediment generated under higher intensities (120 mm/h, 150 mm/h) were significantly different across five vegetation restoration types. NH4+-N and TN were mostly lost through sedimentation, whereas NO3‾-N was primarily leached in runoff (80%–88%). N leaching was positively correlated with runoff, sedimentation rate, geometric mean diameter, mean weight diameter, and fine sediment particles (